The Total Lunar Eclipse of Sunday, January 20<sup>th</sup>, 2019

The Total Lunar Eclipse of
Sunday, January 20th, 2019

This will be the last total lunar eclipse visible in its entirety in Idaho until November, 2022.

January 20, 2019 lunar eclipse phases

Adapted from a diagram by NASA.  Note that, although the moon's orbital motion will cause it to move to the left (east) relative to Earth's shadow, it (and the shadow) will be moving to the upper right (away from the eastern horizon) due to Earth's rotation.  Thus, for observers in Idaho, the moon will be moving higher in the sky relative to the local horizon throughout the eclipse.

Eclipse timeline (all times listed are in Mountain Standard Time (UT-7 hrs.), and rise/set/twilight times are given for Twin Falls, Idaho, USA):

  • 7:13 PM — End of astronomical twilight.  The last trace of the sun's glow disappears in the west.
  • 7:30 PM — Centennial Observatory opens for public telescope viewing, weather permitting.  Please dress warmly!
  • 7:36 PM — First penumbral contact (P1).   The lower edge of the moon begins to enter Earth's penumbral (partial) shadow.  The subtle decrease in illumination of the moon will not be noticeable to the eye.
  • 8:34 PM — First umbral contact (U1).  The moon begins to enter Earth' umbral (full) shadow.  A small, dark "bite" begins to grow ever larger from the moon's lower edge.
  • 9:41 PM — Total phase begins (U2) (second umbral contact).  The moon is completely immersed in Earth's umbra, appearing dark red-orange, orange-brown, or darker depending on global atmospheric conditions.
  • 10:12 PM — Greatest eclipse.  The moon reaches its maximum excursion into the umbral shadow, appearing at its darkest for this eclipse.  For this particular eclipse, the moon passes well north of the center of Earth's full (umbral) shadow, so it will probably not get extremely dark, with the upper left edge noticeably less dark than the lower right, which is deepest into the shadow.
  • 10:43 PM — Total phase ends (U3) (third umbral contact).  The moon begins to emerge from Earth's umbra, with a growing, bright sliver appearing at left edge of the lunar disk.
  • 11:51 PM — Last umbral contact (U4).  The shrinking dark bite disappears from the moon's upper right edge.  The moon is still in the partial (penumbral) shadow, with subtle darkening that lessens toward the lower left.
  • 12:30 AM — Observatory closes.  With the moon mostly out of the penumbral shadow, it will appear completely normal to all but the most discerning eye.
  • 12:48 AM — Last penumbral contact (P4).  The moon has completely exited Earth's shadow, although the subtlety of the shading will render it normal to the eye well before this point.